This invention relates to the dispensing of a relatively small flow of a solid or liquid into a mass of fluid, and, more particularly, to the dispensing of an even, unagglomerated flow of a hydratable material.
In some mineral beneficiation processes, a flocculant is dispensed into a fluid to clarify the fluid of solids (including colloids) that are present in the fluid. The flocculant is a hydratable material that first is wetted by the fluid as it is mixed with the fluid, which is typically water or an aqueous solution. Ideally, the wetted flocculant thereafter chemically reacts with finely divided solids in the fluid to cause them to agglomerate into larger masses. The masses of flocculated solids are removed from the fluid by filtration or other suitable process.
The dispensing of the flocculant into the fluid sometimes presents some problems. In a typical case, the flocculant is a finely divided powder. The flocculant begins to absorb water and become wetted as soon as it contacts the fluid. However, at the same time its molecular structure changes In a manner comparable to polymerization so that it reacts with solids in the fluid to achieve the flocculation reaction. Since the wetting and chemical reactions are occurring generally simultaneously, the flocculant can sometimes itself agglomerate into masses, often termed "fisheyes" in the art, before it has a chance to react with the solids in the fluid. Any such self-agglomerated flocculant is not available to flocculate solids in the fluid, with the result that the flocculation treatment is only partially effective or is wasteful of the expensive flocculant material.
Existing techniques for dispensing flocculant seek to add the flocculant in a flow and rely upon achieving a degree of mixing of the flocculant with the fluid before the flocculant can self-agglomerate. However, it is found that this approach is often not successful, and flocculant lumps are observed in the fluid regardless of the care taken in adding the flocculant. There is therefore a need for an improved approach to dispensing such hydratable materials into fluid masses. The present invention fulfills this need, and further provides related advantages.